Multi-layer film for forming a vacuum packaging bag and method of manufacture

ABSTRACT

A vacuum packaging film with an improved embossed pattern suitable for evacuation of gas from a vacuum packaging bag made of the film. The embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges. The ridges of a first sequence are offset with respect to the ridges of an adjacent second sequence.

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 60/611,114, entitled “MULTI-LAYER FILM FOR FORMING A VACUUM PACKAGING BAG AND METHOD OF MANUFACTURE”, by Hongyu Wu, filed on Sep. 17, 2004, and which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to vacuum packaging film, and more particularly to patterned vacuum packaging film.

BACKGROUND OF THE INVENTION

Vacuum packaging film is used for vacuum sealing of perishable items. Due to the film's versatility in producing vacuum sealed packages of various sizes, its popularity has increased in recent years. As a result, continuous product improvement is required on the part of manufacturers in order to stay competitive. One such improvement has been applying patterns to vacuum packaging bags.

For vacuum packaging bags with smooth inner surfaces (i.e., inner surfaces that do not have a pattern), the bag surfaces sometimes stick together when air is evacuated from the bag during vacuum packaging. This may result in air pockets within the seal and degraded seal integrity. In response to this problem, manufacturers may imprint or emboss a pattern onto vacuum packaging film used to form the vacuum packaging bags. The pattern helps prevent vacuum packaging bag surfaces from sticking together during vacuum packaging by forming channels along the grooves of an imprinted pattern—or forming channels between raised portions of an embossed pattern—when the surfaces of the bag are face to face. The pattern may be applied to one or both of the inner surfaces of the vacuum packaging bag.

While imprinting or embossing a pattern onto vacuum packaging film is generally desirable, imprinting or embossing a pattern introduces new problems. For example, embossed patterns may be less durable than smooth surfaces. In general, the farther an embossed pattern sticks out from the surface of vacuum packaging film, the less durable the film becomes. Moreover, thicker embossing—or deeper grooves—typically consumes more material and may be harder to apply to or form into the film. Thicker embossing—or deeper grooves—also typically results in thicker vacuum packaging film, which makes the film heavier and less compact so it takes up more space in storage. Furthermore, if the surface of a vacuum packaging film has a high concentration of raised areas, there will be fewer channels formed when evacuating a vacuum packaging bag made of the film. Since there are fewer channels, even if relatively few channels become blocked gas may be trapped and air pockets formed, resulting in degraded seal integrity.

Accordingly, what is needed is a vacuum packaging film with an improved embossing pattern to reduce embossing thickness, to reduce the concentration of raised areas on vacuum packaging film, or to increase the number of channels formed when the vacuum packaging film is used in a vacuum packaging application.

SUMMARY OF THE INVENTION

The present invention fills these needs by providing a vacuum packaging film with an improved embossed pattern suitable for evacuation of gas from a vacuum packaging bag made of the film. In an aspect of the present invention, the embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges. The ridges of a first sequence are offset with respect to the ridges of an adjacent second sequence.

A method for making vacuum packaging film, in accordance with an aspect of the present invention, includes heat extruding a first material onto a spinning cooling roll and heat extruding a second material onto the spinning cooling roll. The first and second extruded materials bond and form a film of the first material with a plurality of roughly parallel sequences of substantially collinear ridges of the second material forming a pattern on the film. The pattern is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made from the film.

A vacuum packaging bag made of the vacuum packaging film according to an aspect of the present invention includes a first sheet and a second sheet. The first and second sheets are formed of the vacuum packaging film. The second sheet has a footprint substantially similar to the first sheet. The first and second sheets are arranged with respective second layers facing one another. The first and second sheets are sealed on opposing lateral sides and an end side, whereby the first and second sheets form a vacuum packaging bag with an opening for insertion of food or other product. The vacuum packaging bag is sealable at the opening.

A vacuum packaging bag roll, suitable for forming vacuum packaging bags, made of the vacuum packaging film according to an aspect of the present invention includes a first sheet and a second sheet. The first and second sheets are formed of the vacuum packaging film. The second sheet has a footprint substantially similar to the first sheet. The first and second sheets are arranged with respective second layers facing one another. The first and second sheets are sealed on opposing lateral sides, wherein portions of the bag roll may be cut from the bag roll thereby creating a partially formed bag having opposing ends that are unsealed. Sealing one end of a partially formed bag forms a vacuum packaging bag with an opening at the other end.

An advantage of the present invention is that the configuration of ridges of an embossed pattern allows gas to flow around blockages through alternative paths. Moreover, a patterned vacuum packaging film can be produced economically.

These and other advantages of the present invention will become apparent to those skilled in the art after reading the following descriptions and studying the various figures of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a conceptual view of a vacuum packaging film.

FIG. 2 depicts alternative vacuum packaging film patterns for the vacuum packaging film depicted in FIG. 1.

FIG. 3 depicts a conceptual view of layers of a multi-layer vacuum packaging film according to the present invention.

FIGS. 4A, 4B, 4C, and 4D depict exemplary systems for manufacturing vacuum packaging film in accordance with the present invention.

FIG. 5 depicts a flowchart illustrating an exemplary method for manufacturing vacuum packaging film in accordance with the present invention.

FIG. 6 depicts a vacuum packaging bag roll made of vacuum packaging film according to the present invention.

FIG. 7 depicts a vacuum packaging bag made of vacuum packaging film according to the present invention.

FIG. 8 is a conceptual view of a cross-section of a vacuum packaging film according to the present invention.

FIG. 9 depicts a conceptual view of a cross-section of a vacuum packaging film with a channel for evacuation according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a new embossed pattern for a surface of a vacuum packaging film. The term embossed, as used herein, is intended to mean that a pattern is raised or in relief and is not intended to imply a particular technique—such as cold-pressing, extrusion, or imprinting—used to apply the pattern. The embossed pattern is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of the film. The pattern, due to its advantageous configuration, should reduce the relative concentration and height of embossed ridges on the surface of the film. In an embodiment, the embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges, where ridges of a first sequence are offset with respect to ridges of an adjacent second sequence. The offset ridges are operable to form multiple channel paths through which gas flows during evacuation of the vacuum packaging bag. Due to the offset, if a channel becomes clogged or collapsed, gas will seek one of many other alternative paths. The vacuum packaging film and an exemplary method for manufacturing the film will now be described. It should be noted that certain extraneous details were left out of the subsequent description in an effort to not unnecessarily obscure the true spirit and scope of the present invention.

FIG. 1 depicts a conceptual view of a vacuum packaging film 100. The vacuum packaging film includes a plurality of ridges 102 arranged as a plurality of sequences of collinear ridges 104. The sequences of collinear ridges 104 are parallel to one another. In addition, the ridges 102 of adjacent sequences of collinear ridges 104 are offset with respect to one another. This offset facilitates rerouting of gas when the ridges 102 form walls of an evacuation channel. Consider, for example, a gas flow 110. If the gas flow 110 encounters a blockage, the gas flow 110 can seek alternative routes to the left or right of the blockage. In the example of FIG. 1, the gas flow 110 flows to the right for illustrative purposes only.

FIG. 2 depicts alternative vacuum packaging film patterns for the vacuum packaging film 100 (FIG. 1). FIG. 2 depicts a zigzag pattern 200A, an alternative zigzag pattern 200B, and a wavy pattern 200C. It should be noted that ridges 202 of a sequence 204 may be only approximately collinear. For the purposes of this application, for any set of ridges, if each of the ridges intersect a given line, then the ridges are referred to as “substantially collinear” along the line. Accordingly, the sequence 204 may be described as a sequence of substantially collinear ridges. It should further be noted that some of the ridges of a first series of substantially collinear ridges are not necessarily parallel to the ridges of a second series of substantially collinear ridges. Nevertheless, for the purposes of this application, for any given series of sequences of substantially collinear ridges, if the lines along which the substantially collinear ridges align are parallel to one another, the sequences are referred to as “roughly parallel.” Accordingly, the sequences of substantially collinear ridges of FIG. 2A may be described as roughly parallel.

The alternative zigzag pattern 200B and wavy pattern 200C are analogous to the zigzag pattern 200A so they are not described in detail herein. Moreover, it should be noted that the patterns of FIG. 2 are depicted for exemplary purposes only. A great many different roughly parallel sequences of ridges with an offset would fall within the scope of this aspect of the present invention. Similarly, an uneven pattern (not shown) of ridges could have the effect of providing alternate routes if a channel is blocked.

FIG. 3 depicts a conceptual view of exemplary layers of a vacuum packaging film 100 according to the present invention. The vacuum packaging film 100 includes a structural layer 302, a bonding layer 304, a gas-impermeable layer 306, a bonding layer 308, and a hear-sealable resin layer 310. The structural layer 302 provides strength to the multi-layer film. The bonding layer 304 bonds the structural layer 302 to the gas-impermeable layer 306. The gas-impermeable layer may be made of polyester, polyamide (nylon) or some other material that serves as an oxygen barrier to protect the contents of a sealed bag made from the vacuum packaging film 100. A bonding layer 308 bonds the gas-impermeable layer 306 to the heat-sealable resin layer 310. The heat-sealable resin layer 310 may be made of a polyethylene resin or any other heat-sealable material that is food safe. In an embodiment, the heat-sealable material must be food safe because it forms the inner layer of a bag used to store food. In an alternative embodiment, the heat-sealable material need not be food safe.

It should be noted that the vacuum packaging film 100 could be made with as few as two layers, a gas-impermeable layer and a heat-sealable resin layer, bonded together without a bonding layer between them. The bonding layers and structural layer are optional in this embodiment. Moreover, in an alternative, the heat-sealable resin layer could be replaced with any sealable material, such as glue.

FIGS. 4A, 4B, 4C, and 4D depict exemplary systems for manufacturing vacuum packaging film in accordance with the present invention. FIG. 4A illustrates an apparatus 400A for manufacturing vacuum packaging film in accordance with an embodiment of the invention. The apparatus 400A includes a multi-layer extruder 402 that extrudes a plastic melt 404 onto a roller 406, which may be a cooling roller. The roller 406 is embedded with an inverse pattern that turns in the direction of arrow 408. The inverse pattern is for imprinting a pattern onto the plastic melt 404. As the multi-layer extruder extrudes the plastic melt 404, the plastic melt 404 comes in contact with the turning roller 406. As the melt is cooled, a pattern is formed on the melt at the same time due to the presence of the inverse pattern. As a result, a multi-layer vacuum packaging film 410 emerges.

FIG. 4B illustrates an apparatus 400B for manufacturing vacuum packaging film in accordance with an embodiment of the invention. The apparatus 400B is much like the apparatus 400A (FIG. 4A), but includes a cooling plank 422. Instead of the multi-layer extruder 402 extruding plastic melt 404 directly onto the roller 406, the multi-layer extruder 402 extrudes plastic melt 404 onto the cooling plank 422. The cooling plank 422 has an inverse pattern. As the plastic melt 404 flows along the cooling plank 422, the plastic melt 404 congeals and is simultaneously imprinted with a pattern, due to the presence of the inverse pattern. The congealed plastic flows onto the roller 406, and a multi-layered, patterned vacuum packaging film 410 emerges as it is pulled along by the roller 406, which may or may not also have an inverse pattern.

FIG. 4C illustrates an apparatus 400C for manufacturing vacuum packaging film in accordance with an embodiment of the invention. The apparatus 400C is much like the apparatus 400A (FIG. 4A), but includes an air knife 432. As the plastic melt 404 flows onto the roller 406, the air-knife 432 selectively etches a pattern onto the melt 404 with concentrated blasts of air 434. Additionally, blasts of air 434 also cause the melt 304 to congeal into multi-layered, patterned vacuum packaging film 410 that is pulled along by the roller 406.

FIG. 4D illustrates an apparatus 400D for manufacturing vacuum packaging film in accordance with an embodiment of the invention. The apparatus 400D is much like the apparatus 400A (FIG. 4A), but includes an inverse vacuum 442. As the plastic melt 404 flows onto the roller 406, the inverse-vacuum 442 selectively “pulls” a pattern onto the melt. Additionally, the inverse vacuum 442 also causes the melt to congeal into multi-layered, patterned vacuum packaging film 410 that is pulled along by roller 406.

FIG. 5 depicts a flowchart 500 illustrating an exemplary method for manufacturing vacuum packaging film in accordance with the present invention. The flowchart starts at block 502 with heat extruding a first material onto a roller. The flowchart ends at block 504 with heat extruding a second material onto the roller such that the first and second extruded materials bond and form a film of the first material with multiple roughly parallel sequences of substantially collinear ridges of the second material forming a pattern that is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of the film.

It should be noted that the method of manufacture using a multi-layer extruder 402 is for illustrative purposes only. While the manufacturing technique can produce a vacuum packaging film with the advantageous qualities described herein, some other technique for imprinting a pattern onto a vacuum packaging film will also suffice, as is well-known in the art of vacuum packaging film manufacturing. It should further be noted that, depending on the technique for imprinting the pattern, a multi-layer vacuum packaging film may have the pattern imprinted on one or more of the multiple layers, or the pattern may simply be embossed only on the heat-sealable resin layer.

FIG. 6 depicts a vacuum packaging bag roll 600 made of vacuum packaging film 100 according to the present invention. The vacuum packaging bag roll 600 includes a first sheet 602 of vacuum packaging film 100 bonded to a second sheet 604 of vacuum packaging film 100 on opposing lateral sides 606. The second sheet 604 has a footprint that is substantially similar to the footprint of the first sheet 602 so that the sheets fit together. The first sheet 602 and second sheet 604 are arranged with respective heat-sealable resin layers 310 (FIG. 3) facing one another. Accordingly, the heat-sealable resin layer 310 may be referred to as the inner layer of a bag roll. Similarly, the structural layer 302 (FIG. 3) may be referred to as the outer layer of a bag roll. Portions of the vacuum packaging bag roll 600 can be cut from the bag roll thereby creating a partially formed bag having opposing ends that are unsealed.

FIG. 7 depicts a vacuum packaging bag 700 made of vacuum packaging film 100 according to the present invention. The vacuum packaging bag 700 includes a first sheet 702 of vacuum packaging film 100 bonded to a second sheet 704 of vacuum packaging film 100 on opposing lateral sides and an end side 706. The first and second sheets form the vacuum packaging bag 700 with an opening for insertion of food or other product. In an embodiment, the vacuum packaging bag is heat-sealable at the opening.

FIG. 8 is a conceptual view 800 of a cross-section of a vacuum packaging film 100 according to the present invention. In the example of FIG. 8, the embossed pattern, as exemplified by the ridge 102, is imprinted on the gas-impermeable layer 306 and the heat-sealable resin layer 310. As discussed earlier, the vacuum packaging film 100 could be made with additional layers, such as the bonding layer 308 (FIG. 3), some or all of which could also be imprinted with the embossed pattern.

FIG. 9 depicts a conceptual view 900 of a cross-section of a vacuum packaging film 100 with a channel 910 for evacuation according to the present invention. A sheet 902 is placed against the packaging film 100 such that the embossed ridges of the vacuum packaging film 100 form walls of the channel 910. The sheet 902 may or may not have the same embossed pattern as the vacuum packaging film 100, but an embossed pattern is omitted from FIG. 9 for illustrative purposes only. The heat-sealable resin layer 310 is the inner layer and the gas-impermeable layer 306 is the outer layer, also for illustrative purposes only.

While this invention has been described in terms of certain embodiments, it will be appreciated by those skilled in the art that modifications, permutations and equivalents thereof are within the inventive scope of the present invention. It is therefore intended that the following appended claims include such modifications, permutations and equivalents as fall within the true spirit and scope of the present invention. Moreover, the embodiments described herein are for exemplary purposes only and should not be construed to capture every embodiment of the invention. The invention is limited only by the claims. 

1. A multi-layer film suitable for use in forming a vacuum packaging bag, said multi-layer film comprising: a first layer made of a first material; and a second layer made of a second material that is formed onto said first layer, said second layer having a pattern that is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of said film, said pattern including a plurality of roughly parallel sequences of substantially collinear ridges, wherein ridges of a first sequence of said parallel sequences of substantially collinear ridges are offset with respect to an adjacent second sequence of said parallel sequences of substantially collinear ridges.
 2. The film of claim 1, wherein said first material is a gas-impermeable material, and wherein said first layer is a gas-impermeable layer.
 3. The film of claim 1, wherein said pattern is embossed onto said first layer as well as said second layer.
 4. The film of claim 1, wherein said second material is a heat-sealable resin, and wherein said second layer is a heat-sealable resin layer.
 5. The film of claim 4, wherein said heat-sealable resin is a polyethylene resin.
 6. The film of claim 1, further comprising a third material in between said first material and said second material, said third material forming a bonding layer between said first and second layers.
 7. The film of claim 1, further comprising a fourth material and a fifth material, said fourth material forming a bonding layer between said first layer and a fifth layer made of said fifth material, wherein said fifth layer is a structural layer for providing structural strength to said film.
 8. The film of claim 1, wherein said substantially collinear ridges have a striped pattern.
 9. The film of claim 1, wherein said substantially collinear ridges have a zigzag pattern.
 10. The film of claim 1, wherein said substantially collinear ridges have a wave pattern.
 11. The film of claim 1, wherein said substantially collinear ridges have an uneven pattern.
 12. A method of manufacturing a multi-layer film for use in vacuum packaging applications, said multi-layer film having a pattern that operates to form channels suitable for evacuation of gas when said multi-layer film is used in the creation of a vacuum packaging bag, said method comprising the acts of: heat-extruding a first material onto a roller; and heat-extruding a second material onto said roller such that said first and second extruded materials bond and form a film of said first material with a plurality of roughly parallel sequences of substantially collinear ridges of said second material forming a pattern on said film, said pattern operable to form channels suitable for evacuation of gas from a vacuum packaging bag made from said film.
 13. The method of claim 12, wherein said first material is a gas-impermeable material, said method further comprising forming a gas-impermeable layer as a first layer of said film.
 14. The method of claim 14, further comprising the act of heat-extruding a third material in between said first and second material, wherein said third material forms a bonding layer between a first layer made of said first material and a second layer made of said second material.
 15. The method of claim 12, further comprising the act of heat-extruding a fourth material and a fifth material to respectively form a bonding layer and a structural layer, wherein said bonding layer bonds said structural layer to a first layer made of said first material, and wherein said structural layer provides structural strength to said film.
 16. The method of claim 12, further comprising the act of controlling a temperature of said roller in order to properly effectuate cooling and formation of said first and second layers.
 17. The method of claim 12, wherein the act of applying a pattern to said first and second layers is accomplished by providing said pattern on the circumferential surface of said roller.
 18. The method of claim 12, wherein the act of applying a pattern to said first and second layers is accomplished by using an air knife to shape said first and second materials subsequent to extrusion.
 19. The method of claim 19, wherein said air-knife includes an inverse vacuum, further comprising imparting said pattern on said first and second materials using said inverse vacuum.
 20. A vacuum packaging bag for holding food or other product, said vacuum packaging bag comprising: a first sheet formed of a multi-layer plastic film, said multi-layer plastic film including: a first layer made of a first material; and a second layer made of a second material that is laminated onto said first layer, said second layer having an embossed pattern that is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of said film, said embossed pattern including a plurality of roughly parallel sequences of substantially collinear ridges, wherein ridges of a first sequence of said parallel sequences of substantially collinear ridges are offset with respect to an adjacent second sequence of said parallel sequences of substantially collinear ridges; a second sheet formed of said multi-layer plastic film, said second sheet having a footprint substantially similar to said first sheet, wherein said first and second sheets are arranged with respective second layers facing one another, said first and second sheets sealed on opposing lateral sides and at an end side, whereby said first and second sheets form a vacuum packaging bag having an opening for insertion of food or other product, said vacuum packaging bag sealable at said opening. 